Electromagnetically Driven Valve

ABSTRACT

An electromagnetically driven valve includes a driven valve having a stem and carrying out reciprocating motion along a direction in which the stem extends, a disc support base, a lower disc having one end coupled to the stem and the other end supported by the disc support base so as to allow free oscillation of the lower disc and oscillating around a central axis extending at the other end, and a lower torsion bar provided so as to extend along the central axis and fixed to the other end. The lower torsion bar has a fix portion fixed to the disc support base, and a phase angle thereof around the central axis with respect to the disc support base can be adjusted. With such a structure, the driven valve can carry out reciprocating motion in a stable manner, and energy loss can be reduced.

TECHNICAL FIELD

The present invention generally relates to an electromagnetically drivenvalve, and more particularly to an electromagnetically driven valve of arotary drive type used in an internal combustion engine and driven byelectromagnetic force and elastic force.

BACKGROUND ART

Japanese Utility Model Laying-Open No. 61-200919 discloses a knock pinhaving serration formed on an outer circumferential surface of a pinbody along an axial direction thereof In addition, Japanese UtilityModel Laying-Open No. 61-200920 discloses a knock pin having an elasticbody provided on an outer circumferential surface of a pin body, theelastic body being pressed against and brought in contact with a wallsurface of an insertion hole.

Japanese Utility Model Publication No. 14-20004 discloses an apparatusfor preventing loosening of a male screw, which includes a male screwthreaded on an outer circumference and having a notch in a part of theouter circumference, and a locknut arranged on an outer circumference ofthe notch. Moreover, Japanese Utility Model Publication No. 37-9013discloses a screw of which loosening is prevented, which includes afemale screw shaped like a case, a screw screwed into the female screw,and a set screw having a disc-shaped head and screwed in an axialdirection from a head of the female screw toward an inner end of thescrew.

An electromagnetically driven valve called a rotary drive type includesa driven valve having a stem and carrying out reciprocating motionbetween a valve-opening position and a valve-closing position, a dischaving one end in abutment to an end of the stem and the other endsupported by a disc support base in a hinged manner, and anelectromagnet applying electromagnetic force to the disc. Theelectromagnetically driven valve further includes a torsion bar providedat the other end of the disc and moving the driven valve toward thevalve-opening position and a helical spring arranged on an outercircumference of the stem and moving the driven valve toward thevalve-closing position. Elastic force of the spring and electromagneticforce generated as a result of current supply to the electromagnet causethe disc to oscillate around the other end. The movement of the disc istransmitted to the stem through one end, whereby the driven valvecarries out reciprocating motion.

In such an electromagnetically driven valve, a torsion bar and a helicalspring are provided such that the disc is located at a positionintermediate between the valve-opening position and the valve-closingposition while the electromagnetic force is not applied. Based on thisassumption, electromagnetic force for overcoming spring force of thesesprings is calculated at each lift position of the driven valve, andcurrent supply to the electromagnet is controlled in accordance with acalculation result.

On the other hand, in the torsion bar and the helical spring, error inshape inevitable in the manufacturing step or assembly error withrespect to the disc support base or the stem is produced, which resultsin failure in accurate setting of the disc to the intermediate position.In such a case, error in spring load imposed on the driven valve at eachlift position is produced, and accurate electromagnetic force forovercoming the spring load cannot be calculated. Then, movement of thedriven valve becomes unstable, a speed of the valve when seated (soundproduced from operation) is high, or electric power for correcting sucherror is wasted in the electromagnet.

DISCLOSURE OF THE INVENTION

In order to solve the above-described problems, an object of the presentinvention is to provide an electromagnetically driven valve attainingstable reciprocating motion of the driven valve and reduction in energyloss.

An electromagnetically driven valve according to the present inventionis actuated by cooperation of electromagnetic force and elastic force.The electromagnetically driven valve includes: a driven valve having avalve shaft and carrying out reciprocating motion along a direction inwhich the valve shaft extends; a supporting member provided at aposition apart from the driven valve; an oscillating member having oneend coupled to the valve shaft and the other end supported by thesupporting member so as to allow free oscillation of the oscillatingmember and oscillating around an axis extending at the other end; and atorsion spring provided so as to extend along the axis and fixed to theother end. The torsion spring includes a fix portion fixed to thesupporting member, and a phase angle thereof around the axis withrespect to the supporting member can be adjusted.

According to the electromagnetically driven valve structured as above,the fix portion is provided, so that the torsion spring is attached tothe supporting member with a phase angle around the axis extending atthe other end being adjusted, and fixed to that position. Accordingly,the spring load imposed by the torsion spring onto the oscillatingmember can accurately be set to a value determined in design. Here, whenthe oscillating member actually oscillates, no error is produced betweenthe spring load imposed by the torsion spring onto the oscillatingmember and the spring load calculated in design. Therefore,electromagnetic force based on the spring load in design is applied tothe oscillating member, whereby stable reciprocating motion of thedriven valve is achieved. As it is not necessary to apply theelectromagnetic force for eliminating the error in the spring load,waste of electric power in the electromagnetically driven valve can beprevented.

Preferably, a plurality of oscillating members are provided, with adistance from each other in a direction in which the valve shaftextends. According to the electromagnetically driven valve structured asabove, an effect as described above can be obtained in theelectromagnetically driven valve adopting a parallel link mechanism.

Preferably, the fix portion includes an outer circumferential surface ofthe torsion spring, having serration formed. The supporting member hasan opening for receiving the fix portion. An inner wall of the openinghas serration formed, which is engaged with the serration formed on thefix portion. According to the electromagnetically driven valvestructured as above, engagement between the serration formed on theouter circumferential surface of the torsion spring and the serrationformed on the inner wall of the opening is shifted, so that a phaseangle of the torsion spring around the axis with respect to thesupporting member can be adjusted. In addition, as engagement betweenthe serrations is strong, the torsion spring can further reliably befixed in the adjusted position.

Preferably, the fix portion includes an outer circumferential surface ofthe torsion spring, implemented as a tapered surface. The supportingmember has an opening for receiving the fix portion. An inner wall ofthe opening has a tapered surface formed, which is pressed against andbrought in contact with the tapered surface formed on the fix portion.According to the electromagnetically driven valve structured as above,the torsion spring is pressed into the opening with the tapered surfacesbeing slid, so that a phase angle of the torsion spring around the axiswith respect to the supporting member can arbitrarily be adjusted. Inaddition, as wedge force is produced between the outer circumferentialsurface of the torsion spring and the inner wall of the opening, thetorsion spring can reliably be fixed in the adjusted position. Moreover,the outer circumferential surface of the torsion spring should only betapered. Therefore, even if workability of the torsion spring is poor,such a shape can readily be obtained.

Preferably, the fix portion includes an outer circumferential surface ofthe torsion spring, having a male screw formed. The supporting memberhas an opening for receiving the fix portion. An inner wall of theopening has a female screw formed such that the male screw formed on thefix portion is screwed in. A locknut is fastened to the opening from aside opposite to a direction in which the fix portion is inserted.According to the electromagnetically driven valve structured as above,an angle for the torsion spring to be screwed into the opening ismodified, so that a phase angle of the torsion spring around the axiswith respect to the supporting member can arbitrarily be adjusted. Inaddition, loosening of the torsion spring can be prevented by repulsiveforce produced between the locknut and the torsion spring. Accordingly,the torsion spring can reliably be fixed in the adjusted position.

As described above, according to the present invention, anelectromagnetically driven valve attaining stable reciprocating motionof the driven valve and reduction in energy loss can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing an electromagnetically drivenvalve according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing an electromagnet in FIG. 1.

FIG. 3 is a perspective view showing a lower disc (an upper disc) inFIG. 1.

FIG. 4 is a perspective view of cross-section of the electromagneticallydriven valve along the line IV-IV in FIG. 1.

FIG. 5 is a cross-sectional view of the electromagnetically driven valvealong the line V-V in FIG. 4.

FIG. 6 is an end view of a lower torsion bar viewed in a direction of anarrow VI in FIG. 5.

FIG. 7 is a schematic diagram showing the upper disc and the lower discat an oscillation end on a valve-opening side.

FIG. 8 is a schematic diagram showing the upper disc and the lower discat an intermediate position.

FIG. 9 is a schematic diagram showing the upper disc and the lower discat an oscillation end on a valve-closing side.

FIG. 10 is a graph showing a relation between a lift amount of thedriven valve and resultant force of the upper torsion bar and the lowertorsion bar.

FIG. 11 is a cross-sectional view showing an electromagnetically drivenvalve according to a second embodiment of the present invention.

FIG. 12 is a cross-sectional view showing a variation of theelectromagnetically driven valve in FIG. 11.

FIG. 13 is a cross-sectional view showing an electromagnetically drivenvalve according to a third embodiment of the present invention.

FIG. 14 is a cross-sectional view showing the step of adjusting loadbalance in the electromagnetically driven valve in FIG. 13.

BEST MODES FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described with reference tothe drawings.

First Embodiment

The electromagnetically driven valve according to the present embodimentimplements an engine valve (an intake valve or an exhaust valve) in aninternal combustion engine such as a gasoline engine or a diesel engine.In the present embodiment, description will be given assuming that theelectromagnetically driven valve implements an intake valve, however, itis noted that the electromagnetically driven valve is similarlystructured also when it implements an exhaust valve.

Referring to FIG. 1, an electromagnetically driven valve 10 is a rotarydrive type electromagnetically driven valve. As an operation mechanismfor the electromagnetically driven valve, a parallel link mechanism isapplied.

Electromagnetically driven valve 10 includes a driven valve 14 having astem 12 extending in one direction, a lower disc 20 and an upper disc 30coupled to different positions on stem 12 and oscillating by receivingelectromagnetic force and elastic force applied thereto, a disc supportbase 51 provided in parallel to stem 12 at a position apart from stem12, a valve-opening/closing electromagnet 60 (hereinafter, also simplyreferred to as electromagnet 60) provided in disc support base 51 andgenerating the electromagnetic force, and a lower torsion bar 26 and anupper torsion bar 36 provided in lower disc 20 and upper disc 30respectively and applying the elastic force to these discs. Driven valve14 carries out reciprocating motion in the direction in which stem 12extends (a direction shown with an arrow 103), upon receiving theoscillating movement of lower disc 20 and upper disc 30.

Driven valve 14 is mounted on a cylinder head 41 having an intake port17 formed. A valve seat 42 is provided in a position where intake port17 of cylinder head 41 communicates to a not-shown combustion chamber.Driven valve 14 further includes an umbrella-shaped portion 13 formed atan end of stem 12. The reciprocating motion of driven valve 14 causesumbrella-shaped portion 13 to intimately contact with valve seat 42 orto move away from valve seat 42, so as to open or close intake port 17.In other words, when stem 12 is elevated, driven valve 14 is positionedat a valve-closing position. On the other hand, when stem 12 is lowered,driven valve 14 is positioned at a valve-opening position.

Stem 12 is constituted of a lower stem 12 m continuing fromumbrella-shaped portion 13 and an upper stem 12 n connected to lowerstem 12 m with a lash adjuster 16 being interposed. Lash adjuster 16with a property more likely to contract and less likely to expandattains a function as a buffer member between upper stem 12 n and lowerstem 12 m. Lash adjuster 16 accommodates registration error of drivenvalve 14 at the valve-closing position, and brings umbrella-shapedportion 13 into contact with valve seat 42 in an ensured manner. Lowerstem 12 m has a coupling pin 12 p projecting from its outercircumferential surface formed, and upper stem 12 n has a coupling pin12 q projecting from its outer circumferential surface formed in aposition away from coupling pin 12 p.

In cylinder head 41, a valve guide 43 for slidably guiding lower stem 12m in an axial direction is provided, and a stem guide 45 for slidablyguiding upper stem 12 n in an axial direction is provided in a positionaway from valve guide 43. Valve guide 43 and stem guide 45 are formedfrom a metal material such as stainless steel, in order to endurehigh-speed slide movement with respect to stem 12.

Referring to FIGS. 1 and 2, electromagnet 60 is provided in disc supportbase 51 at a position between lower disc 20 and upper disc 30.Electromagnet 60 is constituted of a valve-opening/closing coil 62 and avalve-opening/closing core 61 formed from a magnetic material and havingattraction and contact surfaces 61 a and 61 b (hereinafter referred toas surface 61 a, surface 61 b). Valve-opening/closing core 61 has ashaft portion 61 p extending in a direction orthogonal to the directionin which stem 12 extends. Valve-opening/closing coil 62 is provided in amanner wound around shaft portion 61 p, and implemented by a monocoil (acoil implemented by a continuous wire).

Disc support base 51 further includes a valve-opening permanent magnet55 and a valve-closing permanent magnet 56 located on a side opposite tovalve-opening permanent magnet 55 with electromagnet 60 beinginterposed. Valve-opening permanent magnet 55 has an attraction andcontact surface 55 a (hereinafter referred to as surface 55 a), and aspace in which lower disc 20 oscillates is defined between surface 55 aand surface 61 b of electromagnet 60. In addition, valve-closingpermanent magnet 56 has an attraction and contact surface 56 a(hereinafter referred to as surface 56 a), and a space in which upperdisc 30 oscillates is defined between surface 56 a and surface 61 a ofelectromagnet 60.

Referring to FIGS. 1 and 3, lower disc 20 has one end 22 and the otherend 23, and extends from the other end 23 to one end 22 in a directionintersecting stem 12. Lower disc 20 is constituted of an arm portion 21having rectangular surfaces 21 a and 21 b formed and extending betweenone end 22 and the other end 23, and a shaft-receiving portion 28 havinga hollow cylindrical shape and provided at the other end 23. Surfaces 21a and 21 b face surface 61 b of electromagnet 60 and surface 55 a ofvalve-opening permanent magnet 55, respectively.

Arm portion 21 has a notch 29 formed on the side of one end 22, andelongated holes 24 are formed in opposing wall surfaces of notch 29. Acentral axis 25 extending in a direction orthogonal to a direction fromone end 22 to the other end 23 is defined in the other end 23. Shaftreceiving portion 28 has a through hole 27 formed, which extends alongcentral axis 25.

Upper disc 30 is shaped similarly to lower disc 20, and one end 32, theother end 33, an arm portion 31, a surface 31 b, a surface 31 a, a notch39, an elongated hole 34, a shaft receiving portion 38, a through hole37, and a central axis 35 corresponding to one end 22, the other end 23,arm portion 21, surface 21 a, surface 21 b, notch 29, elongated hole 24,shaft receiving portion 28, through hole 27, and central axis 25 oflower disc 20 respectively are formed. Surfaces 31 a and 31 b facesurface 61 a of electromagnet 60 and surface 56 a of valve-closingpermanent magnet 56, respectively. Lower disc 20 and upper disc 30 areformed from a magnetic material.

One end 22 of lower disc 20 is coupled to lower stem 12 m so as to allowfree oscillation of the disc, by insertion of coupling pin 12 p intoelongated hole 24. One end 32 of upper disc 30 is coupled to upper stem12 n so as to allow free oscillation of the disc, by insertion ofcoupling pin 12 q into elongated hole 34.

In the following, a structure of lower torsion bar 26 and a structurefor attachment of lower disc 20 will be described. It is noted thatupper torsion bar 36 and upper disc 30 also have similar structures.

Referring to FIG. 1 and FIGS. 4 to 6, lower torsion bar 26 is fixed atthe other end 23 in such a state that it is inserted into through hole27. Lower torsion bar 26 is formed from a spring steel, and shaped likea bar extending along central axis 25. Lower torsion bar 26 has a fixportion 4 fixed to disc support base 51 at one end thereof Lower torsionbar 26 is rotatably supported by disc support base 51, on a sideopposite to fix portion 4.

An outer circumferential surface 4 a of fix portion 4 has serrationformed. The serration is implemented by grooves extending in the axialdirection and provided side by side in a circumferential direction. Thenumber of grooves provided side by side in the circumferential directionon outer circumferential surface 4 a may be set to 20, for example, oralternatively, it may be set to different number. Disc support base 51has an opening 52 for receiving fix portion 4 formed. An inner wall ofopening 52 has serration formed, which is engaged with the serrationformed on outer circumferential surface 4 a.

When fix portion 4 is inserted in opening 52, the serration formed onouter circumferential surface 4 a of fix portion 4 and the serrationformed on the inner wall of opening 52 are engaged with each other, sothat lower torsion bar 26 is fixed to disc support base 51. The otherend 23 of lower disc 20 is thus supported by disc support base 51 so asto allow free oscillation of the disc around central axis 25. Similarly,the other end 33 of upper disc 30 is supported by disc support base 51so as to allow free oscillation of the disc around central axis 35, withupper torsion bar 36 being interposed. Oscillation of lower disc 20 andupper disc 30 around central axes 25 and 35 respectively can causedriven valve 14 to carry out reciprocating motion.

Lower torsion bar 26 applies elastic force to lower disc 20, in a mannermoving the same clockwise around central axis 25. Upper torsion bar 36applies elastic force to upper disc 30, in a manner moving the samecounterclockwise around central axis 35. While the electromagnetic forcefrom electromagnet 60 is not yet applied, lower disc 20 and upper disc30 are positioned by elastic force of lower torsion bar 26 and uppertorsion bar 36 at a position intermediate between an oscillation end ona valve-opening side and an oscillation end of a valve-closing side.

In the present embodiment, lower torsion bar 26 and upper torsion bar 36are fixed to disc support base 51, with a position where the serrationformed on outer circumferential surface 4 a of fix portion 4 is engagedwith the serration formed on the inner wall of opening 52 beingadjusted. For example, if lower disc 20 and upper disc 30 are positionedcloser to the oscillation end on the valve-opening side with respect tothe intermediate position described above, counterclockwise elasticforce by upper torsion bar 36 overcomes clockwise elastic force by lowertorsion bar 26. Here, for example, in order to increase the elasticforce by lower torsion bar 26, the position of engagement of theserrations should be adjusted such that fix portion 4 of lower torsionbar 26 is shifted clockwise with respect to opening 52. In this manner,fix portion 4 attains a function as a mechanism for adjusting loadbalance between lower torsion bar 26 and upper torsion bar 36. By meansof fix portion 4, lower disc 20 and upper disc 30 can accurately bepositioned at the intermediate position between the oscillation end onthe valve-opening side and the oscillation end of the valve-closingside.

An operation of electromagnetically driven valve 10 will now bedescribed.

Referring to FIG. 7, when driven valve 14 is at the valve-openingposition, valve-opening/closing coil 62 is supplied with a currentflowing in a direction shown with an arrow 111 around shaft portion 61 pof valve-opening/closing core 61. Here, on a side where upper disc 30 islocated, the current flows from the back toward the front of the sheetshowing FIG. 7. Accordingly, magnetic flux flows invalve-opening/closing core 61 in a direction shown with an arrow 112,and the electromagnetic force attracting upper disc 30 toward surface 61a of electromagnet 60 is generated. On the other hand, lower disc 20 isattracted to surface 55 a by valve-opening permanent magnet 55.Consequently, upper disc 30 and lower disc 20 resist the elastic forceof lower torsion bar 26 arranged around central axis 25, and they areheld at the oscillation end on the valve-opening side shown in FIG. 7.

Referring to FIG. 8, when current supply to valve-opening/closing coil62 is stopped, the electromagnetic force generated by electromagnet 60disappears. Then, upper disc 30 and lower disc 20 move away fromsurfaces 61 a and 55 a as a result of the elastic force of lower torsionbar 26, respectively, and start to oscillate toward the intermediateposition. The elastic force applied by lower torsion bar 26 and uppertorsion bar 36 attempts to hold upper disc 30 and lower disc 20 at theintermediate position. Therefore, at a position beyond the intermediateposition, force in a direction reverse to an oscillating direction actson upper disc 30 and lower disc 20 from upper torsion bar 36. On theother hand, as inertial force acts on upper disc 30 and lower disc 20 inthe oscillating direction, upper disc 30 and lower disc 20 oscillate asfar as the position beyond the intermediate position.

Referring to FIG. 9, at the position beyond the intermediate position, acurrent is again fed to valve-opening/closing coil 62 in a directionshown with arrow 111. Here, on a side where lower disc 20 is located,the current flows from the front toward the back of the sheet showingFIG. 9. Accordingly, magnetic flux flows in valve-opening/closing core61 in a direction shown with an arrow 132, and the electromagnetic forceattracting lower disc 20 toward surface 61 b of electromagnet 60 isgenerated. On the other hand, upper disc 30 is attracted to surface 56 aby valve-closing permanent magnet 56.

Here, upper disc 30 is also attracted to surface 61 a of electromagnet60 by the electromagnetic force generated by electromagnet 60. Here, theelectromagnetic force is stronger between lower disc 20 andelectromagnet 60 because a space therebetween is narrow. Therefore,upper disc 30 and lower disc 20 oscillate from the position beyond theintermediate position to the oscillation end on the valve-closing sideshown in FIG. 9.

Thereafter, current supply to valve-opening/closing coil 62 isrepeatedly started and stopped at a timing described above. In thismanner, upper disc 30 and lower disc 20 are caused to oscillate betweenthe oscillation ends on the valve-opening side and the valve-closingside, so that driven valve 14 can carry out the reciprocating motion asa result of the oscillating movement.

Electromagnetically driven valve 10 according to the first embodiment ofthe present invention is actuated by cooperation of the electromagneticforce and the elastic force. Electromagnetically driven valve 10includes driven valve 14 having stem 12 serving as the valve shaft andcarrying out the reciprocating motion along the direction in which stem12 extends, disc support base 51 serving as the supporting memberprovided at a position apart from driven valve 14, lower disc 20 andupper disc 30 serving as oscillating members having one ends 22 and 32coupled to stem 12 and the other ends 23 and 33 supported by discsupport base 51 so as to allow free oscillation of the disc respectivelyand oscillating around central axes 25 and 35 extending at the otherends 23 and 33, and lower torsion bar 26 and upper torsion bar 36serving as the torsion springs extending along central axes 25 and 35and fixed to the other ends 23 and 33. Lower torsion bar 26 and uppertorsion bar 36 have fix portion 4 fixed to disc support base 51, and aphase angle thereof around central axes 25 and 35 with respect to discsupport base 51 can be adjusted.

Fix portion 4 includes outer circumferential surface 4 a of lowertorsion bar 26 and upper torsion bar 36, having the serration formed.Disc support base 51 has opening 52 for receiving fix portion 4 formed.The inner wall of opening 52 has the serration formed, which is engagedwith the serration formed in fix portion 4.

In the present embodiment, the mechanism for adjusting load balance bymeans of fix portion 4 has been provided in each of lower disc 20 andupper disc 30, however, the mechanism may be provided in either one ofthem. If the mechanism for adjusting load balance is provided in each oflower disc 20 and upper disc 30, load balance between lower torsion bar26 and upper torsion bar 36 can readily be varied. Therefore, elasticforce applied to lower disc 20 and upper disc 30 during oscillation canfreely be adjusted.

According to electromagnetically driven valve 10 in the first embodimentof the present invention as structured above, fix portion 4 is providedin lower torsion bar 26 and upper torsion bar 36, so that lower disc 20and upper disc 30 can accurately be positioned at the intermediateposition between the oscillation ends on the valve-opening side and thevalve-closing side while electromagnetic force from electromagnet 60 isnot applied.

FIG. 10 shows a relation between a lift amount of the driven valve andresultant force of the upper torsion bar and the lower torsion bar, andthe resultant force of upper torsion bar 36 and lower torsion bar 26 isrepresented on the ordinate assuming a direction moving driven valve 14upward as positive. A straight line 76 in FIG. 10 represents a relationbetween the lift amount and the resultant force in design, that is, arelation between the same when lower disc 20 and upper disc 30 areaccurately positioned at the intermediate position while electromagneticforce from electromagnet 60 is not applied. A straight line 78 in FIG.10 represents a relation between the lift amount and the resultant forcewhen lower disc 20 and upper disc 30 are positioned closer to thevalve-opening side with respect to the intermediate position, while astraight line 77 in FIG. 10 represents a relation between the liftamount and the resultant force when lower disc 20 and upper disc 30 arepositioned closer to the valve-closing side with respect to theintermediate position.

As can been seen from comparison of straight lines 76 to 78, if lowerdisc 20 and upper disc 30 are set to a position displaced from theintermediate position, a point where elastic force of two torsion barsare balanced is displaced from a balance point P in design in a rangeindicated by an arrow 79 in FIG. 10. Here, the resultant force of thetwo torsion bars applied to driven valve 14 at each lift positionfluctuates, for example, in a range shown with an arrow 80 in FIG. 10,and error is produced with respect to the resultant force set in design,that is, with respect to the resultant force represented by straightline 76. In the present embodiment, however, lower disc 20 and upperdisc 30 are accurately positioned at the intermediate position betweenthe oscillation ends on the valve-opening side and the valve-closingside, and therefore, no such error is produced. Accordingly, theelectromagnetic force calculated based on the resultant force set indesign is applied to lower disc 20 and upper disc 30, whereby stablereciprocating motion of driven valve 14 can be achieved.

Second Embodiment

An electromagnetically driven valve according to the present embodimentis structured in a manner basically similar to electromagneticallydriven valve 10 in the first embodiment. Therefore, description of aredundant structure will not be repeated.

FIG. 11 shows a region similar to that shown in FIG. 5. Referring toFIG. 11, in the present embodiment, outer circumferential surface 4 a offix portion 4 is formed as a tapered surface. In other words, outercircumferential surface 4 a extends in a manner inclined with respect tocentral axis 25, and is implemented by a side surface of a frustum of acone formed along central axis 25. On the inner wall of opening 52, atapered surface being in surface contact with outer circumferentialsurface 4 a while lower torsion bar 26 is inserted in opening 52 isformed. Fix portion 4 has a hexagonal hole 84 formed from a side of anend surface 4 c of fix portion 4.

Disc support base 51 has a female screw hole 81 formed, which is openedfrom a side of a side surface 51 c and continues to opening 52. A nut 82is tightened into female screw hole 81 with a magnitude of tighteningforce P. Nut 82 has a hexagonal hole 83 penetrating along central axis25 formed. Hexagonal hole 83 is larger than hexagonal hole 84. Nut 82presses end surface 4 c of fix portion 4, so that the tapered surfaceformed on outer circumferential surface 4 a is pressed against andbrought in contact with the tapered surface formed on the inner wall ofopening 52. Here, an angle between central axis 25 and an edge line ofouter circumferential surface 4 a is assumed as θ (a tapered angle ofouter circumferential surface 4 a is 2θ). Then, fastening force N of fixportion 4 with respect to opening 52 having a magnitude of P/tan θ isproduced.

In the present embodiment, a special hexagonal wrench having a throughhole formed in an axial direction and a normal hexagonal wrench are usedto fix lower torsion bar 26 to disc support base 51. More specifically,nut 82 is lightly tightened in such a state that fix portion 4 isinserted in opening 52. Then, the tip end of the special hexagonalwrench is fitted to hexagonal hole 83, and the normal hexagonal wrenchis inserted in the through hole formed in the special hexagonal wrenchfor fitting to hexagonal hole 84. In such a state, lower torsion bar 26is positioned so as to attain an optimal phase angle by turning thenormal hexagonal wrench, and thereafter the special hexagonal wrench isturned. Lower torsion bar 26 is thus fixed in that position.

According to the electromagnetically driven valve in the secondembodiment of the present invention, fix portion 4 includes outercircumferential surface 4 a of lower torsion bar 26 formed as thetapered surface. Disc support base 51 has opening 52 for receiving fixportion 4. The inner wall of opening 52 has the tapered surface formed,which is pressed against and brought in contact with the tapered surfaceformed on fix portion 4.

Disc support base 51 has female screw hole 81 continuing to opening 52formed. Nut 82 serving as a pressing member for pressing end surface 4 cof fix portion 4 and pressing and contacting the tapered surfaces formedon outer circumferential surface 4 a and the inner wall of opening 52with each other is fastened to female screw hole 81. Fix portion 4 hashexagonal hole 84 formed from the side of end surface 4 c, which servesas a first tool insertion hole in which the hexagonal wrench serving asa tool for turning fix portion 4 around rotation axis 25 is inserted.Nut 82 has hexagonal hole 83 formed, which serves as a second toolinsertion hole in which the special hexagonal wrench serving as a toolfor exposing hexagonal hole 84 for fastening nut 82 is inserted.

FIG. 12 shows a variation of the electromagnetically driven valve inFIG. 11. Referring to FIG. 12, in the present variation, a plate 71joined to end surface 4 c of fix portion 4 is provided, instead of nut82 in FIG. 11. Plate 71 extends over end surface 4 c as far as sidesurface 51 c of disc support base 51, like a collar. Plate 71 has anelongated hole 71 h formed in a position above side surface 51 c, whichis elongated in a circumferential direction around central axis 25.Plate 71 is fastened to disc support base 51 by a bolt 72 insertedthrough elongated hole 71 h. In the present variation, bolt 72 isfastened with plate 71 being turned, so as to fix lower torsion bar 26at an optimal phase angle.

In the present embodiment, description has been given solely inconnection with lower torsion bar 26, however, fix portion 4 asdescribed above should only be provided in at least one of lower torsionbar 26 and upper torsion bar 36.

According to the electromagnetically driven valve in the secondembodiment of the present invention structured as above, an effectsimilar to that in the first embodiment can be obtained. In addition,according to the present embodiment, the mechanism for adjusting loadbalance by means of fix portion 4 is implemented by abutment of thetapered surfaces. Therefore, lower torsion bar 26 can be positioned atany phase angle around central axis 25, whereby adjustment of loadbalance with a further higher degree of freedom can be achieved. Inaddition, as large fastening force can be generated by virtue of wedgeeffect, loosening of lower torsion bar 26 from opening 52 can beprevented.

Third Embodiment

An electromagnetically driven valve according to the present embodimentis structured in a manner basically similar to electromagneticallydriven valve 10 in the first embodiment. Therefore, description of aredundant structure will not be repeated.

FIG. 13 shows a region similar to that shown in FIG. 5. Referring toFIG. 13, in the present embodiment, outer circumferential surface 4 a offix portion 4 has a male screw formed. Fix portion 4 has a hexagonalhole 88 formed from a side of end surface 4 c of fix portion 4. On theother hand, the inner wall of opening 52 has a female screw formed, intowhich a male screw formed on outer circumferential surface 4 a isscrewed. A locknut 86 is fastened to opening 52 from a side opposite tofix portion 4, and end surface 4 c of fix portion 4 is pressed by an endsurface 86 c of locknut 86 facing end surface 4 c. Locknut 86 has a hole87 formed, which is penetrated in a direction in which central axis 25extends.

The step of adjusting load balance in the electromagnetically drivenvalve shown in FIG. 13 will now be described. Referring to FIG. 14,initially, fix portion 4 is fastened to opening 52. Referring to FIG.13, locknut 86 is lightly fastened from the opposite side, and thehexagonal wrench is fitted into hexagonal hole 88 through hole 87. Insuch a state, lower torsion bar 26 is positioned at an optimal phaseangle by turning the hexagonal wrench, and locknut 86 is further rigidlyfastened. Lower torsion bar 26 is thus fixed to that position.

According to the electromagnetically driven valve in the thirdembodiment of the present invention, fix portion 4 includes outercircumferential surface 4 a of lower torsion bar 26 having the malescrew formed. Disc support base 51 has opening 52 for receiving fixportion 4. The inner wall of opening 52 has the female screw formed suchthat the male screw formed on fix portion 4 is screwed in. Locknut 86 isfastened to opening 52 from the side opposite to the direction in whichfix portion 4 is inserted.

Fix portion 4 has hexagonal hole 88 formed from the side of end surface4 c, which serves as a tool insertion hole in which the hexagonal wrenchserving as a tool for turning fix portion 4 around rotation axis 25 isinserted. Locknut 86 has hole 87 for exposing hexagonal hole 88 formed.

In the present embodiment, description has been given solely inconnection with lower torsion bar 26, however, fix portion 4 asdescribed above should only be provided in at least one of lower torsionbar 26 and upper torsion bar 36.

According to the electromagnetically driven valve in the thirdembodiment of the present invention, an effect similar to that in thefirst embodiment can be obtained. In addition, according to the presentembodiment, the mechanism for adjusting load balance by means of fixportion 4 is implemented by a screw structure. Therefore, lower torsionbar 26 can be positioned at any phase angle around central axis 25,whereby adjustment of load balance with a further higher degree offreedom can be achieved.

The first to third embodiments have described an example adopting aparallel link mechanism in an electromagnetically driven valve of arotary drive type, however, the present invention is not limitedthereto. The present invention is applicable to an electromagneticallydriven valve including one disc having one end coupled to stem 12 andthe other end supported by disc support base 51 so as to allow freeoscillation of the disc and a plurality of electromagnets arranged aboveand below the disc and alternately applying electromagnetic force to thedisc, in a manner similar to the first to third embodiments.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

INDUSTRIAL APPLICABILITY

The present invention is mainly utilized as an intake valve or anexhaust valve in a gasoline engine, a diesel engine, or the like.

1. An electromagnetically driven valve actuated by cooperation ofelectromagnetic force and elastic force, comprising: a driven valvehaving a valve shaft and carrying out reciprocating motion along adirection in which said valve shaft extends; a supporting memberprovided at a position apart from said driven valve; an oscillatingmember having one end coupled to said valve shaft and the other endsupported by said supporting member so as to allow free oscillation ofthe oscillating member and oscillating around an axis extending at saidother end between an oscillation end on a valve-opening side of saiddriven valve and an oscillation end on a valve-closing side of saiddriven valve; and a torsion spring provided so as to extend along saidaxis and fixed to said other end; wherein said torsion spring includes afix portion fixed to said supporting member, and a phase angle of thefix portion around said axis with respect to said supporting member canbe adjusted, and as a result of adjustment of said phase angle, aposition of said oscillating member is adjusted to a positionintermediate between the oscillation end on the valve-opening side ofsaid driven valve and the oscillation end on the valve-closing side ofsaid driven valve by elastic force while electromagnetic force is notapplied to said oscillating member.
 2. The electromagnetically drivenvalve according to claim 1, wherein a plurality of said oscillatingmembers are provided, with a distance from each other in a direction inwhich said valve shaft extends.
 3. The electromagnetically driven valveaccording to claim 1, wherein said fix portion includes an outercircumferential surface of said torsion spring having serration formed,said supporting member has an opening for receiving said fix portion,and an inner wall of said opening has serration formed, which is engagedwith the serration formed on said fix portion.
 4. Theelectromagnetically driven valve according to claim 1, wherein said fixportion includes an outer circumferential surface of said torsion springimplemented as a tapered surface, said supporting member has an openingfor receiving said fix portion, and an inner wall of said opening has atapered surface formed, which is pressed against and brought in contactwith the tapered surface formed on said fix portion.
 5. Theelectromagnetically driven valve according to claim 1, wherein said fixportion includes an outer circumferential surface of said torsion springhaving a male screw formed, said supporting member has an opening forreceiving said fix portion, and an inner wall of said opening has afemale screw formed such that the male screw formed on said fix portionis screwed in, and a locknut is fastened to said opening from a sideopposite to a direction in which said fix portion is inserted.
 6. Amethod of manufacturing the electromagnetically driven valve of claim 1,comprising the steps of: adjusting said phase angle such that saidoscillating member is positioned at a position intermediate between anoscillation end on a valve-opening side of said driven valve and anoscillation end on a valve-closing side of said driven valve; and fixingsaid fix portion of which phase angle has been adjusted to saidsupporting member.